if your looking for a bio on brutus try plutarchs "life of brutus" it can be found in the makers of rome printed by penguin, or the loeb classics series. it has all the information you need regarding brutus. Im pretty sure this was the main source shakespeare used when writing "Julius caesar". there is no doubt he died at philippi. As for portia, she aparently commited suicide by eating hot coals after caesars death but before brutus'. I dont know what happened to caesars wife but would be highly interested if anybody does, along with servilia.